Thread with Pyjnuis object not detaching

[Dewald du Plooy]

Hi,

I'm creating a thread in my python android application which reads and writes to Bluetooth. Bluetooth functionality is obtained through Pyjnius. Everything works OK, but when the thread closes I get the message:

native thread exited without detaching.

If I don't use Pyjnius, the thread opens and closes without problem.

I get the following output when the thread closes:

V/BluetoothSocket.cpp(10961): availableNative
V/BluetoothSocket.cpp(10961): abortNative
V/BluetoothSocket.cpp(10961): ...asocket_abort(57) complete
V/BluetoothSocket.cpp(10961): destroyNative
V/BluetoothSocket.cpp(10961): ...asocket_destroy(57) complete
D/dalvikvm(10961): threadid=13: thread exiting, not yet detached (count=0)
D/dalvikvm(10961): threadid=13: thread exiting, not yet detached (count=1)
E/dalvikvm(10961): threadid=13: native thread exited without detaching
E/dalvikvm(10961): VM aborting
F/libc    (10961): Fatal signal 11 (SIGSEGV) at 0x00bed330 (code=13805624)
I/DEBUG   (10957): SET
I/DEBUG   (10957): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
I/DEBUG   (10957): Build fingerprint: 'samsung/espressorfxx/espressorf:4.0.4/IMM76D/P3100XWBLJ1:user/release-keys'
I/DEBUG   (10957): pid: 10961, tid: 10979  >>> org.kivy.pygame:python <<<
I/DEBUG   (10957): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr deadd00d
I/DEBUG   (10957):  r0 00000000  r1 00be2e58  r2 00000000  r3 00000000

So my questions are:

1. Is there a specific way I should remove objects created with Pyjnius?
2. May I use Pyjnius in threads?

Regards,

Dewald

[LostCitizen]

Can you post the code you're running?

Regards

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[dewa...@gmail.com]

Hi LostCitizen,

Thank you for your interest in helping :)

I've attached the code so that you can easily test it on your device:

1. change "dev_name" variable to your PC name

2. copy "main.py" and "android.txt" to your device's kivy folder after

3. Run "pc_side_bt3.py" on your PC

4. Launch the kivy app with Kivy Launcher 1.8

5. Click on disconnect button

6. App will close in a few seconds. The output can be obtained with the "adb logcat" tool.

Here is the hopefully minimal example of my code:

from kivy.lang import Builder
from kivy.app import App
from kivy.logger import Logger

import time
import threading

from jnius import autoclass

BluetoothAdapter = autoclass('android.bluetooth.BluetoothAdapter')
BluetoothDevice = autoclass('android.bluetooth.BluetoothDevice')
BluetoothSocket = autoclass('android.bluetooth.BluetoothSocket')
UUID = autoclass('java.util.UUID')

dev_name = 'DEWALD-PC'
strUUID = '94f39d29-7d6d-437d-973b-fba39e49d4ee'

class CommLinkAndroidBT(object):

    def __init__(self, dev_name, strUUID):       
        self.dev_name = dev_name
        self.strUUID = strUUID
        self.open()
        
    def open(self):
        paired_devices = BluetoothAdapter.getDefaultAdapter().getBondedDevices().toArray()
          
        for device in paired_devices:
            if device.getName() == self.dev_name:
                self.socket = device.createRfcommSocketToServiceRecord(UUID.fromString(self.strUUID))
                self.send_stream = self.socket.getOutputStream()
        self.socket.connect()
    
    def write(self, mesg):
        self.send_stream.write(mesg)        
        self.send_stream.flush()    #necessary?
        
    def close(self):
        self.socket.close()
        Logger.info('closing')
        
class UpdateThread(threading.Thread):

    def __init__(self, threadID, name, driver):
        threading.Thread.__init__(self)
        self.exitFlag = False
        self.commLink = CommLinkAndroidBT(dev_name, strUUID)

    def run(self):

        while not self.exitFlag:            
            self.commLink.write("A")
            time.sleep(1)

        self.commLink.close()

if __name__ == '__main__':
    kv = '''
BoxLayout:
    Button:
        text: 'Disconnect'
        on_release: app.disconnect()
    '''

    class Bluetooth(App):

        def on_start(self):            
            self.updateThread = UpdateThread(1, "UpdateThread", self)
            self.updateThread.start()            

        def build(self):
            return Builder.load_string(kv)                        

        def disconnect(self):
            Logger.info('Calling disconnect')
            self.updateThread.exitFlag = True
            self.updateThread.join()

    Bluetooth().run()

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[dewa...@gmail.com]

Hi,

Ok, I've now confirmed that this has nothing to do with bluetooth. You can achieve a crash with any Pyjnius object. I will send a separate email for it shortly.

Best Regards,

Dewald

[Brian Knapp]

Was a solution reached?  I need to ship some code using this.

[stephane...@gmail.com]

Just getting started with Kivy on Android.  I have a pyjnius thread accessing USB resources and am running into this issue.  Right now I'm following the suggestion from here: https://github.com/kivy/pyjnius/issues/107
Essentially, don't exit a thread that uses pyjnius.

[Brent Picasso]

I'm running into this problem as well - it's proving to be a tremendous problem for our android app. I also commented on the github issue.

Any ideas how to resolve this issue? Might this approach help?

http://yltechblog.blogspot.com/2013/05/jni-detaching-threads-native-thread.html

Any help is very much appreciated.

-Brent